Glass fiber reinforced poly(vinyl chloride) blend with improved heat

Abstract

A high temperature PVC resin blend is made by blending from 60 to 85 parts PVC with no more than 40 parts of a ('alpha-SAN') copolymer of alpha-methyl styrene ('AMS'), styrene ('S') and acrylonitrile ('AN'), and less than 20 parts by wt additives including stabilizers, antioxidants, lubricants, and processing aids. In addition, an impact modifier may be added. The blend with particularly sized glass fibers, may be thermoformed at an elevated processing temperature and pressure, to provide a reinforced composite in which the PVC is covalently bonded to the glass fiber. The composite has a substantially higher HDT and equivalent tensile strength, compared to that of a similarly reinforced, unblended PVC composite, without sacrificing the novel composite's other desirable physical properties. The glass is sized with an aminosilane coupling agent, and, a polymer film former selected from the group consisting of (i) a polymer with a nitrogen-containing repeating unit such as an amine, amide, ureido, or urethane group, and (ii) a dispersible or emulsifiable epoxide polymer, which composite, upon extraction with THF, and a subsequent XPS examination, yields a C1(2p)/C(1s) ratio of at least 0.91, and more preferably of at least 1.13. Glass fibers, thus sized, provide cohesive bonding of the resin, so the composite fails in cohesive failure. A unique sequence of mixing the bland ingredients with glass fiber provides optimum properties in the composite. The sequence requires formation of a single phase of PVC and alpha-SAN copolymer before dispersing the glass fibers in the blend.